1. Field of the Invention
This invention relates to control devices for hybrid vehicle power transmitting devices. More particularly, it relates to a hybrid vehicle power transmitting device, including an engine, composed of an internal combustion engine serving as a drive power source to run a vehicle, and an electric motor, and a technology of starting up the engine during a switchover from a motor drive mode to an engine drive mode.
2. Description of the Related Art
In the related art, there has been known a hybrid vehicle drive device wherein drive torque, delivered from a main power source composed of an engine, a first electric motor and a differential mechanism, is transferred to drive wheels through an output shaft to which a second electric motor is connected via an automatic transmission. With such a hybrid vehicle drive device, a control device has heretofore been known in which a vehicle occupant is prevented from suffering an increasing shock due to the overlapping between a start-up shock of the engine and a shifting shock of the automatic transmission.
To this end, the shifting of the automatic transmission is interrupted during the execution of a control for starting up the engine to commence a shifting operation of the automatic transmission after the engine has been substantially started up. Such a control device for the hybrid vehicle drive device is disclosed in, for instance, Patent Publication 1 (Japanese Patent Application Publication 2004-208417).
Further, there has been known a control device for a hybrid vehicle power transmitting device including (i) a differential mechanism composed of a first rotary element connected to an engine, a second rotary element connected to a first electric motor and a third rotary element connected to a power transmitting path extending to drive wheels and a second electric motor, and (ii) an automatic shifting portion forming part of the power transmitting path extending from the differential mechanism to the drive wheels to function the an automatic transmission. Such a control device for the hybrid vehicle power transmitting device is disclosed in, for instance, Patent Publication 2 (Japanese Patent Application Publication 2005-264762). With such a control device for the hybrid vehicle power transmitting device, the operation was executed such that when starting up the engine, if the power transmitting path of the automatic shifting portion is interrupted with a vehicle remained halted, the first and second electric motors were caused to rotate in the same rotational direction to increase a rotation speed of the engine, after which the engine was started up.
Besides, another technology is disclosed in Patent Publication 3 (Japanese Patent Application Publication 2003-127679).
With the use of such a control device disclosed in Patent Publication 1, it takes a certain time between timing at which a shifting command is output to cause the shifting to be executed in the automatic transmission, and timing at which engaging elements of the automatic transmission are switched to complete a shifting operation. Meanwhile, the shifting of the automatic transmission is interrupted during the execution of the control for starting up the engine. Therefore, if there is a request for executing the shifting in response to a manipulation of a driver during a start-up control of the engine, the completion of the shifting is delayed with respect to the request on the shifting, with accompanying consequence of causing the driver to feel an increase delay in drive torque.
Further, during the motor drive mode with the vehicle driven by an output of the second electric motor while the engine was kept halted, there was a probability in that like a moment under which an accelerator pedal was deeply depressed during the shifting of the automatic shifting portion, the engine was required to start-up as early as possible. In such a moment, the increasing of the engine rotation speed for the start-up of the engine and the shifting operation of the automatic transmission were concurrently executed. This may occur for the first and second electric motors to operate under the same torque controls as those executed for the automatic shifting portion remaining under a non-shifting. During the non-shifting of the automatic shifting portion, there was a need for increasing or decreasing an input rotation speed of the automatic shifting portion for establishing the shifting therein. Thus, there was a likelihood of a difficulty being encountered in rapidly increasing the rotation speed of the engine.
However, the control device for the hybrid vehicle power transmitting device, disclosed in Patent Publication 2, had no particular consideration on the increasing of the rotation speed for the start-up of the engine and the shifting operation of the automatic shifting portion to be concurrently executed.